Nakubaamavalvu epulasitikingezinye izikhathi kubhekwa njengomkhiqizo okhethekile—okuwukukhetha kokuqala kwabantu abenza noma abaklama imikhiqizo yamapayipi epulasitiki yezinhlelo zezimboni noma okumele babe nemishini ehlanzekile kakhulu—ngamafuphi uma sicabanga ukuthi lawa mavalvu awanawo umbono wokusetshenziswa okuvamile. Eqinisweni, amavalvu epulasitiki anamuhla anokusetshenziswa okubanzi, ngoba izinhlobo zezinto ziyaqhubeka nokukhula, futhi abaklami abahle abadinga lezi zinto kusho ukuthi kunezindlela eziningi zokusebenzisa la mathuluzi anemisebenzi eminingi.

IZAKHIWO ZEPULASTIKI

Izinzuzo zamavalvu e-thermoplastic zibanzi—ukugqwala, ukumelana namakhemikhali nokuklwebheka; izindonga zangaphakathi ezibushelelezi; isisindo esincane; ukulula kokufakwa; isikhathi sokuphila isikhathi eside; kanye nezindleko eziphansi zomjikelezo wokuphila. Lezi zinzuzo ziholele ekwamukelweni kabanzi kwamavalvu epulasitiki ezisetshenziswa kwezentengiselwano nasezimbonini njengokusatshalaliswa kwamanzi, ukwelashwa kwamanzi amdaka, ukucubungula insimbi namakhemikhali, ukudla nemithi, izitshalo zikagesi, izindawo zokuhlanza uwoyela kanye namavalvu epulasitiki e-mo angenziwa ngezinto eziningi ezahlukene ezisetshenziswa ezimisweni eziningana. Amavalvu e-thermoplastic avame kakhulu enziwe nge-polyvinyl chloride (PVC), i-chlorinated polyvinyl chloride (CPVC), i-polypropylene (PP), kanye ne-polyvinylidene fluoride (PVDF). Amavalvu e-PVC kanye ne-CPVC avame ukuhlanganiswa nezinhlelo zamapayipi ngeziphetho zesokhethi ezihlanganisiwe, noma iziphetho ezinentambo nezihlanganisiwe; kanti, i-PP kanye ne-PVDF zidinga ukuhlanganiswa kwezingxenye zesistimu yamapayipi, kungaba ubuchwepheshe bokushisa, i-butt- noma i-electro-fusion.

Amavalvu e-thermoplastic asebenza kahle ezindaweni ezigqwalisayo, kodwa awusizo ngokufanayo ekuhlinzekweni kwamanzi okuvamile ngoba awanayo i-lead1, awakwazi ukugqwala futhi awagqwali. Izinhlelo zamapayipi e-PVC kanye namavalvu kufanele ahlolwe futhi aqinisekiswe yi-NSF [National Sanitation Foundation] standard 61 ngemiphumela yezempilo, okuhlanganisa nesidingo se-lead ephansi ye-Annex G. Ukukhetha izinto ezifanele zoketshezi olugqwalisayo kungaphathwa ngokubonisana nomhlahlandlela womenzi wokumelana namakhemikhali nokuqonda umphumela izinga lokushisa elizoba nawo emandleni ezinto zepulasitiki.

Nakuba i-polypropylene inamandla ayingxenye ye-PVC ne-CPVC, inokumelana kwamakhemikhali okuguquguqukayo kakhulu ngoba azikho izinyibilikisi ezaziwayo. I-PP isebenza kahle kuma-acetic acid nama-hydroxide aqinile, futhi ifaneleka nezixazululo ezithambile zama-acid amaningi, ama-alkali, usawoti kanye namakhemikhali amaningi e-organic.

I-PP iyatholakala njengento enombala noma engenawo umbala (wemvelo). I-PP yemvelo yonakaliswa kakhulu yimisebe ye-ultraviolet (UV), kodwa amakhemikhali aqukethe umbala omnyama wekhabhoni ongaphezu kuka-2.5% aqiniswa ngokwanele yi-UV.

Izinhlelo zamapayipi e-PVDF zisetshenziswa ezinhlotsheni ezahlukene zezimboni kusukela kwezemithi kuya kwezezimayini ngenxa yamandla e-PVDF, izinga lokushisa lokusebenza kanye nokumelana kwamakhemikhali nosawoti, ama-asidi aqinile, izisekelo ezincibilikisiwe kanye nezinyibilikisi eziningi eziphilayo. Ngokungafani ne-PP, i-PVDF ayonakaliswa ukukhanya kwelanga; noma kunjalo, ipulasitiki iyabonakala elangeni futhi ingaveza uketshezi emisebeni ye-UV. Ngenkathi ukwakheka kwemvelo kwe-PVDF okungenambala kuhle kakhulu ekusetshenzisweni kwangaphakathi okuhlanzekile kakhulu, ukwengeza umbala obomvu njengombala obomvu wokudla kungavumela ukuvezwa elangeni ngaphandle komphumela omubi endaweni yoketshezi.

Izinhlelo zepulasitiki zinezinselele zokuklama, njengokuzwela ekushiseni nasekukhuleni nasekuncipheni kokushisa, kodwa onjiniyela bangakwazi futhi baklame izinhlelo zamapayipi ezihlala isikhathi eside nezingabizi kakhulu zezindawo ezijwayelekile nezigqwalayo. Okubalulekile ekuklanyweni ukuthi i-coefficient yokwandiswa kokushisa kwamapulasitiki inkulu kunensimbi—i-thermoplastic iphindwe kahlanu kuya kasithupha kunensimbi, isibonelo.

Lapho kuklanywa izinhlelo zamapayipi futhi kucatshangelwa umthelela ekubekweni kwama-valve kanye nezisekelo zama-valve, into ebalulekile okufanele icatshangelwe kuma-thermoplastics ukunwetshwa kokushisa. Ukucindezeleka namandla avela ekukhuleni nasekuncipheni kokushisa kungancishiswa noma kuqedwe ngokuhlinzeka ngokuguquguquka ezinhlelweni zamapayipi ngokushintsha njalo indlela noma ukwethulwa kwezihibe zokunwebeka. Ngokuhlinzeka ngalokhu kuguquguquka ohlelweni lwamapayipi, i-valve yepulasitiki ngeke idingeke ukuthi imunce ukucindezeleka okuningi (Isithombe 1).

Ngenxa yokuthi ama-thermoplastic ayazwela ekushiseni, izinga lokucindezela le-valve liyancipha njengoba izinga lokushisa likhuphuka. Izinto ezahlukene zepulasitiki zinokuwohloka okuhambisanayo nokushisa okwenyukayo. Izinga lokushisa loketshezi kungenzeka kungabi ukuphela komthombo wokushisa ongathinta izinga lokucindezela kwama-valve epulasitiki—izinga lokushisa eliphezulu langaphandle kufanele libe yingxenye yokucatshangelwa komklamo. Kwezinye izimo, ukungaklami izinga lokushisa langaphandle lamapayipi kungabangela ukuwohloka okukhulu ngenxa yokuntuleka kwezisekelo zamapayipi. I-PVC inokushisa okuphezulu kwesevisi okungu-140°F; i-CPVC inokuphakama okungu-220°F; i-PP inokuphakama okungu-180°F; futhi ama-valve e-PVDF angagcina ingcindezi ifinyelela ku-280°F (Isithombe 2).

Ngakolunye uhlangothi lwesikali sokushisa, izinhlelo eziningi zamapayipi epulasitiki zisebenza kahle kakhulu emazingeni okushisa angaphansi kweqhwa. Eqinisweni, amandla okudonsa ayanda kumapayipi e-thermoplastic njengoba izinga lokushisa lehla. Kodwa-ke, ukumelana komthelela kwamapulasitiki amaningi kwehla njengoba izinga lokushisa lehla, futhi ukuqhekeka kubonakala ezintweni zamapayipi ezithintekile. Uma nje ama-valve kanye nohlelo lwamapayipi oluhambisana nawo kungaphazanyiswa, kungaphazanyiswa ukushaywa noma ukungqubuzana kwezinto, futhi amapayipi engawi ngesikhathi sokuphathwa, imiphumela emibi kumapayipi epulasitiki iyancishiswa.

IZINHLOBO ZAMAVALVU E-THERMOPLASTIC

Amavalvu ebhola,ama-valve okuhlola,amavalvu ebhabhathanefuthi ama-valve e-diaphragm ayatholakala kuzo zonke izinto ezihlukene ze-thermoplastic zezinhlelo zamapayipi okucindezela wesheduli 80 ezinezinketho eziningi zokuhlobisa kanye nezesekeli. I-valve yebhola ejwayelekile ivame ukutholakala njengomklamo we-union weqiniso wokusiza ukususwa komzimba we-valve ukuze kulungiswe ngaphandle kokuphazamiseka kwamapayipi okuxhuma. Ama-valve okuhlola e-Thermoplastic ayatholakala njengokuhlola ibhola, ukuhlola i-swing, ukuhlola i-y kanye nokuhlola ikhoni. Ama-valve e-Butterfly ahlangana kalula nama-flange ensimbi ngoba ahambisana nezimbobo zama-bolt, imibuthano yama-bolt kanye nobukhulu obuphelele be-ANSI Class 150. Ububanzi obubushelelezi bangaphakathi bezingxenye ze-thermoplastic bunezela kuphela ekulawuleni okunembile kwama-valve e-diaphragm.

Ama-valve ebhola ku-PVC kanye ne-CPVC akhiqizwa izinkampani eziningana zase-US nezakwamanye amazwe ngobukhulu obuyi-1/2 intshi kuya ku-6 amayintshi anezixhumi zesokhethi, izintambo noma i-flanged. Umklamo wangempela wobumbano wama-valve ebhola wesimanje uhlanganisa amantongomane amabili anamathela emzimbeni, acindezela izimbozo ze-elastomeric phakathi komzimba kanye nezixhumi zokugcina. Abanye abakhiqizi baye bagcina ubude obufanayo bokubeka ama-valve ebhola kanye nezintambo zamantongomane amashumi eminyaka ukuvumela ukushintshwa kwama-valve amadala kalula ngaphandle kokuguqulwa kumapayipi aseduze.

Ama-valve ebhola anezimbobo ze-ethylene propylene diene monomer (EPDM) elastomeric kufanele aqinisekiswe yi-NSF-61G ukuze asetshenziswe emanzini aphuzwayo. Izimbobo ze-elastomeric ze-Fluorocarbon (FKM) zingasetshenziswa njengendlela ehlukile yezinhlelo lapho ukuhambisana kwamakhemikhali kuyinkinga. I-FKM ingasetshenziswa futhi ezinhlotsheni eziningi zezicelo ezihilela ama-mineral acid, ngaphandle kwe-hydrogen chloride, izixazululo zikasawoti, ama-hydrocarbon ane-chlorine kanye namafutha kaphethiloli.

Isithombe 3. Ivalvu yebhola egoqekile enamathiselwe ethangini Isithombe 4. Ivalvu yokuhlola ibhola efakwe ngokuqondile Amavalvu ebhola e-PVC kanye ne-CPVC, angu-1/2-inch kuya ku-2 intshi, ayindlela efanelekile yokusetshenziswa kwamanzi ashisayo nabandayo lapho insizakalo ephezulu yamanzi angethusi ingaba yi-250 psi ku-73°F. Amavalvu ebhola amakhulu, angu-2-1/2 intshi kuya ku-6 intshi, azoba nesilinganiso sokucindezela esiphansi esingu-150 psi ku-73°F. Avame ukusetshenziswa ekuthuthweni kwamakhemikhali, amavalvu ebhola e-PP kanye ne-PVDF (Izithombe 3 no-4), atholakala ngobukhulu obungu-1/2-inch kuya ku-4 intshi anezixhumi zesokhethi, izintambo noma izintambo ezihlanganisiwe ngokuvamile zilinganiswa nensizakalo ephezulu yamanzi angethusi engu-150 psi ekushiseni okuzungezile.

Amavalvu okuhlola ibhola e-thermoplastic athembele ebholeni elinamandla adonsela phansi athile angaphansi kwamanzi, ukuze uma ingcindezi ilahleka ohlangothini oluphezulu, ibhola lizocwila emuva ebusweni bokuvala. Lawa mavalvu angasetshenziswa enkonzweni efanayo namavalvu ebhola epulasitiki afanayo ngoba awalethi izinto ezintsha ohlelweni. Ezinye izinhlobo zamavalvu okuhlola zingafaka iziphethu zensimbi ezingase zingapheli ezindaweni ezigqwalayo.

Isithombe 5. Ivalvu yebhabhathane ene-elastomeric liner. Ivalvu yebhabhathane yepulasitiki enobukhulu obungamasentimitha angu-2 kuya kwangu-24 ithandwa kakhulu ezinhlelweni zamapayipi amakhulu. Abakhiqizi bamavalvu ebhabhathane epulasitiki bathatha izindlela ezahlukene zokwakha nokuvala izindawo. Abanye basebenzisa i-elastomeric liner (Isithombe 5) noma i-O-ring, kanti abanye basebenzisa idiski ene-elastomeric. Abanye benza umzimba ngento eyodwa, kodwa izingxenye zangaphakathi, ezimanzi zisebenza njengezinto zesistimu, okusho ukuthi umzimba wevalvu yebhabhathane ye-polypropylene ungase uqukathe i-EPDM liner kanye ne-PVC disc noma ezinye izinto eziningana ezine-thermoplastics ezivame ukutholakala kanye nezimpawu ze-elastomeric.

Ukufakwa kwevalvu yepulasitiki yebhabhathane kulula ngoba lawa mavalvu enziwe ngendlela yesitayela se-wafer enezimbobo ze-elastomeric eziklanyelwe emzimbeni. Awadingi ukungezwa kwe-gasket. Kubekwe phakathi kwama-flange amabili okuhlangana, ukugoba phansi kwevalvu yebhabhathane yepulasitiki kumele kuphathwe ngokucophelela ngokunyuka ku-torque yebholiti enconywayo ngezigaba ezintathu. Lokhu kwenziwa ukuqinisekisa ukuthi kufakwa ukuvala okulinganayo ebusweni nokuthi akukho ukucindezeleka okungalingani kwemishini okusetshenziswayo kuvalvu.

Isithombe 6. Ivalvu ye-diaphragm Ochwepheshe be-valve yensimbi bazothola imisebenzi ephezulu yamavalvu e-diaphragm epulasitiki anezikhombisi zesondo kanye nesikhundla ezijwayelekile (Isithombe 6); noma kunjalo, ivalvu ye-diaphragm yepulasitiki ingafaka izinzuzo ezithile ezihlukile kufaka phakathi izindonga zangaphakathi ezibushelelezi zomzimba we-thermoplastic. Njengevalvu yebhola yepulasitiki, abasebenzisi balezi valve banenketho yokufaka umklamo we-union wangempela, ongaba usizo kakhulu emsebenzini wokulungisa ivalvu. Noma, umsebenzisi angakhetha ukuxhumeka okuhlanganisiwe. Ngenxa yazo zonke izinketho zomzimba nezinto ze-diaphragm, le valve ingasetshenziswa ezinhlotsheni ezahlukahlukene zamakhemikhali.

Njenganoma iyiphi i-valve, isihluthulelo sokuqalisa ama-valve epulasitiki ukunquma izidingo zokusebenza ezifana namandla omoya noma kagesi kanye namandla e-DC noma e-AC. Kodwa ngepulasitiki, umklami nomsebenzisi kufanele futhi baqonde ukuthi hlobo luni lwendawo oluzozungeza i-actuator. Njengoba kushiwo ngaphambili, ama-valve epulasitiki ayinketho enhle yezimo ezigqwalisayo, ezifaka phakathi izindawo ezigqwalisayo zangaphandle. Ngenxa yalokhu, izinto zokwakha ama-actuator ama-valve epulasitiki ziyinto ebalulekile okufanele icatshangelwe. Abakhiqizi bama-valve epulasitiki banezinketho zokuhlangabezana nezidingo zalezi zindawo ezigqwalisayo ngesimo sama-actuator ambozwe ngepulasitiki noma ama-metal cases ambozwe nge-epoxy.

Njengoba lesi sihloko sibonisa, ama-valve epulasitiki namuhla anikeza zonke izinhlobo zezinketho zezinhlelo zokusebenza ezintsha nezimo.